The present invention relates to a polymer encapsulated TiO2 coating formulation and its preparation, more particularly a coating formulation exhibiting improved gloss.
Opacifying pigments such as TiO2 are used in coating formulations to provide whiteness and opacity (hiding) to conceal the substrate upon which the coating is applied. Formulators desire to maximize hiding while minimizing the amount of opacifying pigment used in the formulation. To that end, the development of an efficient composition for polymer encapsulated TiO2 particles by Allen et al. (U.S. Pat. No. 8,283,404) represents a significant advance in improving the efficiency of spacing of TiO2 particles in coating formulations. Subsequently, Bardman et al. (US 2014/0011943) improved upon the discovery of Allen et al. with a process for preparing a virtually grit free aqueous dispersion of TiO2 encapsulating with polymer that is film-forming at ambient temperature.
Although hiding efficiency has been significantly improved, one of the ongoing concerns with formulations containing polymer encapsulated TiO2 particles is gloss development over formulations that do not use encapsulation technology: Larger composite particles give inherently lower gloss than their unencapsulated counterparts. Accordingly, it would be desirable to find a way to improve gloss in coating compositions containing polymer encapsulated TiO2 particles.